INTRODUCTION:: In the frenzied days and weeks following September 11, 2001, many observers called for serious consideration of a national identity system, the centerpiece of which would be some form of national identity card. Such a system was seen mainly as a tool against terrorists and also as a useful response to illegal immigration, identity theft, and electoral fraud. As yet, no member of Congress has introduced legislation to establish a formal national identity system or to require a national identity card, and the war on terrorism has turned to other concerns. Nevertheless, the past three years have seen the most serious and detailed consideration of a national identity system in a generation, and we are probably just one domestic terror attack away from its implementation in some form. Even now, all aliens entering the United States will soon be required to have passports or visas with biometric identifiers.

A national identity system raises a host of policy and legal issues. Among the former, the most important issue is what the purpose of such a system would be and whether it would be worth the inevitable financial and social costs. The answer to that question would help determine the answers to such subsidiary questions as who would be required to carry an identity card, what data would be linked to the card, who would have access to that data, and what uses would be made of it. There are many possible national identity systems and myriad kinds of, and uses for, national identity cards.

Scholarly and popular commentary on the possibility of national identity cards has tended to focus on their effect on individual privacy, or as some have put it, the right to anonymity. Obviously, privacy is an extremely important issue because a national identity card has the potential to alter some fundamental aspects of American life. A national identity card would undoubtedly enhance governmental access to and use of information about each person’s activities, interests, and associations. Imposing identity checks would in all likelihood vastly increase the frequency of contacts with government agents. Although the possible Fourth and Fifth Amendment ramifications of a national identity system have often been acknowledged, they have not been explored in depth. The impact on these constitutional rights would of course depend on the particular features of the system. However, because of their centrality to any likely national identity system, it is worth examining these issues even in the absence of a concrete proposal.

Part II of this Article describes the features most observers regard as essential to a national identity system. The main point of identity checking is to make a connection between the identified individual and a collection of data. To be effective, a national identity system would therefore need to require that people provide identification at certain times or places. This requirement would almost certainly produce new interactions between the populace and law enforcement personnel-a subject regulated by the Fourth Amendment only when it amounts to a seizure of the person. One Fourth Amendment question, then, concerns the occasions on which state agents could demand to see a person’s identity card. As the law stands now, the police may request to see the identification of anyone at any time in a so- called consensual encounter that does not involve seizure of the individual. On the other hand, the demand to see identification usually turns the encounter into an investigative detention, which generally requires that the police have reasonable suspicion of criminality. The United States Supreme Court has, however, approved the use of suspicionless identification checkpoint stops for certain non-criminal purposes, such as border control.

The creation of a duty to carry and present identification at certain times would presumably take place against this background, while also moving some of these doctrines into new territory. Could, for example, every person subjected to an investigative or traffic stop be compelled, on pain of prosecution, to show identification? If so, would a national identity system create an incentive to make more stops, particularly for moving violations? When could compulsory identity checkpoints be sustained under the Fourth Amendment administrative-search rationale? Moreover, would there be Fifth Amendment self-incrimination objections to any of these identification requirements? Part III addresses the constitutional questions raised by governmental requests and demands, in a number of contexts, that a person present an identity card.

An identity check can generate new data as well as draw on existing databases. The Fourth and Fifth Amendments are also potentially implicated by the surveillance and monitoring of a person’s movement and activities through such data collection and retention. This is particularly true of governmental collection of data generated in circumstances in which there might otherwise be some legitimate expectation of privacy, such as information provided to health care or educational institutions or in other registration procedures. Would this data collection be a search under the Fourth Amendment, and, if so, would it be a reasonable one? As to more public encounters, law enforcement personnel may generally observe a person while she is in a public place and may even use common technological aids to do so. Accordingly, some data collection attendant to identity checks would seem to be exempt from Fourth Amendment scrutiny. Would a national identity system’s frequent and thorough monitoring of movement and activities be so unlike more common police surveillance, though, that it would constitute a search and therefore would be regulated by the Fourth Amendment? If so, at the very least, it could not be done as a matter of course. Additionally, a potential source of compelled self-incrimination inheres in this data-generating aspect of a national identity system: the requirement that certain self-reported information be conveyed to official databanks. Part IV explores the Fourth and Fifth Amendment issues raised in the potential data collection and retention features of a national identity system.

This Article is not concerned with the efficacy of a national identification system or whether its benefits, however measured, would outweigh its costs-in other words, whether it is a good idea. The conclusions of this Article are not completely divorced from that question, however. As this Article will demonstrate, to some degree the Fourth Amendment will reduce the potential benefits of a national identification system by standing in the way of practices the system might otherwise employ. In particular, random identification stops would fly in the face of Fourth Amendment jurisprudence. Terrorist profiling checkpoints probably would not pass Fourth Amendment muster, either, though they might in certain circumstances. Identification demands in the course of registration procedures, traffic or investigative stops, or arrests, however, are all acceptable under the Fourth Amendment. Nor does that Amendment stand in the way of requesting, rather than demanding, identification of any person at any time. On the information-gathering side of the process, there are substantial Fourth Amendment questions raised by mandated reporting of personal information produced in the course of everyday life. Though this practice should be regarded as a search, it may not be an unreasonable one, up to a point. This Article concludes that, in contrast to the Fourth Amendment’s substantial challenges, the Fifth Amendment does not present a serious obstacle to the most probable national identity system practices.

Whether all of this discussion leaves the glass of a national identity card half full or half empty depends on one’s perspective. What is fairly clear is that, while the Constitution might bar certain practices and block others depending on their purpose and other features, it would be possible to have a constitutional national identity card system of a fairly comprehensive type. Even where such an identity system would not strictly run afoul of the Fourth and Fifth Amendments, however, an analysis of the interests those provisions are designed to protect provides an insight into the price in privacy and liberty that a national identity card would exact. This Article will also indicate how these effects might be mitigated somewhat in the system’s design. In that sense, this Article hopes to illuminate not only what kind of national identity system the U.S. lawfully could have, but also how it might be designed, and, implicitly, whether we want to have one at all.